Factual error: In one scene a parked car is sitting along the street - it is a '68 Chevy, it has sidelights. Yet the film is set in 1962.
Factual error: The scene where Nightfox steals the Faberge Egg is all wrong. A laser security system must have a photoelectric receptor at the other side to detect if somebody pass between the two devices. As shown in the film, the laser beams points everywhere, so the system can't work and somebody could cross a beam without starting the alarm. Even if it was some weird system based on measuring distance it wouldn't work - if the laser hits the floor at an angle it won't bounce back to the source, it will reflect towards the ceiling.
Factual error: In the very first scene in the film when the magazine covers are flashing up, the very first one has a headline which says "loose that belly". For a film whose title has the word "lose" in it, you'd think that they could spell this properly.
Factual error: At the graduation carnival at the end of the movie, Danny enters wearing a letterman's sweater and explains to his buddies that he earned it by lettering in track. However, on his left sleeve are two stripes, indicating that he lettered in two separate years. Since you are only awarded a stripe for each year you letter, and since Danny was a senior when he lettered in track, his Rydell letterman's sweater should have had only one red stripe on his left arm.
Factual error: When Morty is showing Michael how to use the remote, Michael rewinds to a family vacation in 1976. A childhood friend of his invites everyone over to his parents' RV to watch Three's Company. Three's Company didn't premiere until 1977.
Factual error: In one of the first major scenes where Matt Franklin and Tori Frederking are being introduced at the rental store - there is a shot where you can see the entrance of the store, and there is an electronic article surveillance detector on either side of the entrance to the store. This technology for use in a video rental store (for VHS tapes) did not exist in the 1980s.
Factual error: When the results list is posted at the regional competition. "Wooster, MA" is printed next to Zoey Bloch and Avril Dishaw. The correct spelling of the city is Worcester. Wooster is in Ohio.
Factual error: In the second last scene, when Rachel is leaving Singapore for New York, Nick went onboard to propose, and convinced her to stay in Singapore for one more night. However, that's not possible in Singapore as there are strict laws stating that those that enter the departure area must have a boarding pass, with the purpose of leaving the country. Those that have a boarding pass but have no intention to depart the country will be prosecuted, and in 2018 40 people were arrested for various reasons, such as sending a friend off and meeting their idols, etc.
Factual error: In the scene in the church where Ian is being baptized, he is in black shorts. In the Greek Orthodox Church, he would be required to wear white when being baptized.
Factual error: When Bill and Ted grab Beethoven, we are shown the piano he was playing which is a Steinweg (Steinweg later changed his name to Steinway when he immigrated to the United States). Steinweg made their first piano in 1835, and the model shown was built in Braunschweig so must have been made after 1858, but Beethoven died in 1827, years before a Steinweg piano existed. Also the onscreen graphic says it's 1810. (00:47:50)
Factual error: Opening the blank envelope, Marta finds the fragment of the toxicology report. It is signed "Office of the chief medical examiner, Norfolk County, Massachusetts." But then it writes also the address of said office, which is in Marlborough. Marlborough is also the city when Marta resides, and where the lawyers' letters we see come from. But Marlborough is also a city in the Middlesex county, not Norfolk. (01:28:25)
Factual error: In the scene when everyone is in the white Hummer, the vehicle is moving north on the Las Vegas Strip; on the right is Bally's and the Flamingo, with Treasure Island straight ahead in the distance. Yet a few seconds later, when Joy asks the driver to let them out, they are in front of the fountains at Bellagio, which indicates that they are now travelling south on the Strip - yet we never see the Hummer change direction or turn around.